Reprogramming Axial Level Identity to Rescue Neural-Crest-Related Congenital Heart Defects.

The cardiac neural crest arises in the hindbrain, then migrates to the heart and contributes to critical structures, including the outflow tract septum. Chick cardiac crest ablation results in failure of this septation, phenocopying the human heart defect persistent truncus arteriosus (PTA), which trunk neural crest fails to rescue. Here, we probe the molecular mechanisms underlying the cardiac crest's unique potential. Transcriptional profiling identified cardiac-crest-specific transcription factors, with single-cell RNA sequencing revealing surprising heterogeneity, including an ectomesenchymal subpopulation within the early migrating population. Loss-of-function analyses uncovered a transcriptional subcircuit, comprised of Tgif1, Ets1, and Sox8, critical for cardiac neural crest and heart development. Importantly, ectopic expression of this subcircuit was sufficient to imbue trunk crest with the ability to rescue PTA after cardiac crest ablation. Together, our results reveal a transcriptional program sufficient to confer cardiac potential onto trunk neural crest cells, thus implicating new genes in cardiovascular birth defects.